Skip to main content

Full text of "Elby CGS735 Panther Series Synthacon filter builder's Guide"

See other formats

Panther Series - CGS735 Synthacon Filter 

Construction is relatively straightforward and requires assembly of the main board and two Panther Support 
modules. Construction should follow normal assembly guidelines (see General Assembly Guide). 

Assembly of the main board includes the fitting of a 
Panther Carrier board to support the OUT jack. The 
jack should first be mounted on to the carrier board. 
The 4-way header should be fitted on to the main 
board. The carrier board should then be loose fitted 
on to the header and the assembly offered up to the 
front panel. Tighten the pot nuts while checking the 
position of the carrier board at the same time. With 
the pots fully tightened you should finalise 
positioning of the carrier board aiming to get the 
carrier roughly parallel to the main board, tightening 
the jack fixing nut when satisfied. With the carrier 
board correctly positioned solder the 4 header pins 
from the top side of the carrier board. 

A similar process should be carried out for the 
jack/carrier board on the Panther Pot Support board 
which will fit in to the middle column of the panel. 

When all boards have been assembled and 
mounted to the front panel, add the interconnecting 
ribbon cable connectors. 


The following describes a quick (but dirty) approach to tuning this 
module as described by Ken Stone. 

Initially, set the controls as follows:- 

• Set CV SPAN TRIM (P206) fully anti-clockwise 

• Set RESONANCE to maximum 

• Set HP, BP and LP LEVEL to maximum 

• Set CV LEVEL to maximum 

• If required, adjust RESONANCE TRIM (P202) until the module 
stops oscillating 

• Feed a LFO square wave (~5Hz, 10Vp-p OV-centred) in to CV 
IN with no signal at the inputs 

• Adjust CV REJECT (P201 ) for minimum thump 

• Adjust the RESONANCE TRIM so that the screech can be controlled. It will depend on the initial 
frequency pot setting somewhat, so you will need to tweak it so you have acceptable resonance at 
the low frequencies, while not being uncontrollable or stoppable at the top of the frequency range 

• CV SPAN ADJUST - adjust it so you get more or less one octave per volt. Don't waste too much time 
here. There is no way it will be either accurate or thermally stable. 

Be aware that unstable and "nasty" resonances are a feature of the Sallen-key filter. 


Elby Designs - Laurie Biddulph 

9 Follan Close, Kariong, NSW 2250, Australia 

1 of 2 

Panther Series - CGS735 Synthacon Filter 


The Panther Series of modules have been designed to be compatible with the popular Doepfer range of 
EuroRack modules and consequently uses a matching connector. 

The red stripe on the power cable represents pin 1 on the IDC connector which is the -12V rail. 

All Panther Series boards use a boxed 16-way IDC header with a polarising key. Pin 1 on the power 
connector is towards the edge of the board. 

Please pay particular attention to the orientation of the power cable and connector to prevent possible 
damage to the system. 


Elby Designs - Laurie Biddulph 

9 Follan Close, Kariong, NSW 2250, Australia 

2 of 2